1. Technical Field
The present invention relates to an underrun protection arrangement for vehicles that include a frame and an impact element arranged in a position that corresponds to an anticipated stress from a force in the event of a possible collision with another vehicle. At least one link element is provided that is firmly connected to the impact element and is fixed so that it can pivot in relation to the frame. An energy-absorbing element is included that connects the impact element to the frame and which is designed to be compressed in the event of a pivoting movement by the impact element.
A primary utilization of the invention is in connection with heavier commercial vehicles, particularly in order to prevent a passenger vehicle from penetrating under the commercial vehicle in the event of a possible head-on collision between the commercial vehicle and the passenger vehicle.
2. Background Art
Larger motor vehicles, such as commercial vehicles, are often designed with a relatively high ground clearance. One major reason for such design is the need to be able to use the vehicle when driving on uneven ground. Today""s commercial vehicles normally have a ground clearance at the front of the vehicle on the order of 40-50 cm.
This fact that a commercial vehicle normally has a relatively high ground clearance can present a road safety risk. This is due to the fact that in any head-on collision between the commercial vehicle and a passenger car, there is a risk that the front section of the passenger car will penetrate under the front of the commercial vehicle and thus become wedged between the roadway and the front underside of the commercial vehicle. This can lead to the front of the commercial vehicle penetrating the passenger compartment of the passenger car with enormous force, which in turn may result in serious injuries to the occupants of the vehicle. In some instances, the commercial vehicle can even continue forwards and roll over the passenger car.
Various solutions have been suggested for solving the aforementioned problem. The commercial vehicle itself may be designed with a lowered front; that is to say, having a front end in which the ground clearance is so low that a passenger car does not have room to penetrate under the commercial vehicle and become wedged between the larger vehicle and the roadway in the event of a collision. Such a measure, however, is at odds with the aforementioned desire for high ground clearance in order to facilitate driving on uneven ground. This need, therefore, precludes a reduction of the ground clearance in many types of commercial vehicle.
Another solution to this problem is to provide the commercial vehicle with a special underrun protection in the form of a reinforced structure, such as a force-absorbing beam element arranged horizontally at the front of the commercial vehicle. More specifically, such a beam element is arranged in a position that corresponds to an anticipated stress from a force in the event of a collision with a passenger car. By means of such an element, it is possible to prevent a passenger car from penetrating under the front of the commercial vehicle.
Such underrun protection can furthermore be arranged so that it is energy-absorbing and absorbs energy in the event of stressing during a collision. This further reduces the risk of serious injuries in the event of a collision.
A previously known energy-absorbing underrun protection is shown in the document EP-A-0557733. This underrun protection includes an impact element that is pivotally suspended in a vehicle frame by way of two articulated arms. The underrun protection further comprises an energy-absorbing piston and cylinder arrangement for absorbing energy in the event of stress acting on the impact element.
This known construction carries a disadvantage in that, because of the arrangement with the aforementioned articulated arms, it comprises a large number of moving parts, which makes it unnecessarily complicated, and carries a risk that its function may become impaired. Furthermore, the construction is to some extent unstable in the event of lateral stresses; that is to say, during a collision sequence in which a passenger car collides with the impact element at a certain angle in relation to the longitudinal direction of the vehicle. In such situations there is a risk that this known construction will give way under relatively low impact stresses.
The known construction, moreover, affords limited scope for regulating the energy absorption in a controlled manner during a collision. In this respect, there is a general problem regarding the need to adapt the energy-absorbing capacity of an underrun protection to an anticipated situation in the event of a collision between a passenger car and a commercial vehicle.
An object of the present invention is to provide an improved energy-absorbing underrun protection for commercial vehicles that functions reliably with controlled energy absorption under impact stress during a collision.
The above-mentioned object is achieved by means of an arrangement of the aforementioned type, but include special features including at least one locking element designed to permit pivoting movement only in the event of a stress acting on the impact element with a force that exceeds a predetermined limit.
By means of the invention, a stress (force) experienced during a collision can be absorbed with minimum possible injury to the occupants of the passenger car, which are the persons most at risk of injury in the event of a collision between a passenger car and a commercial vehicle.
According to a preferred embodiment of the invention, the locking element comprises (includes, but is not limited to) at least one retaining bolt which is arranged to extend through each link element and which is designed to maintain a fixed connection between the link element and the frame until the limit is reached. In this way, controlled energy absorption is obtained under impact stress.
According to one particular embodiment of the invention, the force/stress limit after which collapse is permitted is defined as an anticipated magnitude of such a force/stress expected to be experienced in the event of a collision with a passenger car following an essentially complete compression of crumple zones provided in the passenger car. The controlled energy absorption can thus be optimally adapted to the impact stress and the sequence that occurs in an anticipated crash situation between a passenger car and a commercial vehicle.
A further object of the invention is to provide an improved energy-absorbing underrun protection that is laterally stable. In this sense, it is meant that the arrangement can withstand deformation when acted upon entirely or partially from the side; that is, transverse to the direction of travel of the vehicle as stated above. This object is achieved at least in part because the link element overlaps a bracket to which the link element is fixed along an area that is designed to meet predetermined requirements regarding stress acting on the impact element in an entirely or partially transverse direction to the longitudinal direction of the vehicle.
Very good lateral stability can be obtained, in particular, if the link element is formed with an essentially L-shaped component having two plate-like side elements in which a first side element extends essentially transversely to the longitudinal direction of the impact element and a second side element extends essentially in the longitudinal direction of the impact element, and the side elements are connected to one another.